Structural joint



s'riw 1 Laurence S. Lachman, Forest 1: ,1:

Application April 10, 1939, Serial No. 267,011

2 Claims. (Cl. 189-82) This invention relates to improved methods ofjoining and securing structural members together, such as are formed,for example, in grills, gratings, bridge decking, and the like.

The grill of this invention is of the general nature comprisingsubstantially longitudinal members preferably made of metal intersectedby lighter, transversely extending members, preferably made of metal,and united together in a.

19 simple manner to form a strong, rigid construction which places themembers under compression. v

The detailed objects of this invention will be apparent from thefollowing description vof sev- 15 eral forms thereof.

This invention resides substantially in the combination, construction,arrangement and relative location of parts,all in accordance with thisdisclosure.

In the accompanying drawings, Figure 1 is a perspective view of aportion of a grill in accordance with this invention; Figure 2 is aperspective view of one of the transverse members;

gure 3 is a perspective view of one of the longitudinal members; Figure4 is a perspective ,view of a portion of a grill showing the membersassembled but without the fastening means in place;

Figure 5 is a cross-sectional view taken on the line 5-5 of Figure 4;Figure 6 is a cross-sectional view taken on the line fi-S of Figure 1;

Figure 7 is a plan view of one of the jolnts; Figure 8 is across-sectional view similar to Figure 6 showing a modified form offastening means:

Figure 9 is a cross-sectional view similar to Figure 6 of a modifiedstructure employing a rivet as a fastening means: and Figures 10 and IIare elevational views of the longitudinal and transverse membersrespectively iormed for use with the rivet fastening means of 5 8 V N 1In grill work of the type herein disclosed, it is desirable that the,members be preloaded, that is,

placed under compression, with the object in view of forming a strong,rigid grill work which does 50 not become loose under, thestmlns 01 use.An

object of this invention is the provision or iasten-- '55 the membersunder compression.

One form of the invention is illustrated in Figures 1 to 7, inclusive.The longitudinal members I, which are in the form of fiat wide bars, areprovided with slots 3 which are of the same depth as the depth of thetransverse members 2. The transverse members are likewise in bar formbut are of less depth than the longitudinal members. They are providedwith the slots 4 which extend about half-way down the depth thereof. Informing a grill of these members the bars 2 are nested in the slots 3 ofthe bars I which are so spaced that the slots of the two sets of barsare in alignment, as is clear from Figure 4. This forms at eachintersection a hollow square, as indicated at 5. In order to secure thebars together in accordance with this invention it is only necessary todrive into these hollow squares hardened screws 6 which under the forceof the blows applied thereto rotate as they move into the hollow squaresuntil they are seated, as indicated in Figure 6. As they move thethreads on their surface cut complementary threads in the walls definingthe hollow squares. It will be seen that the screws are selected as tosize so that the. diameter thereof at the base of the threads just formsa snug fit in the hollow squares 5. By this means it is possible to veryquickly unite the bars the longitudinal members are indicated at landthe transverse members at l3. The longitudinal members III are providedwith slots H which are as deep as the transverse members l3 are wide, asbefore. However, intermediate the ends of these slots the walls thereofdiverge for a short distance, asshown at l2. In the case of the slot Itin the transverse members I3 the base thereof is similarly expanded, asindicated at 15. In other words, the flaring slots l2 and I5 have thesame taper and are of the same length. When the transverse bars areassembled in the slots I I of the longitudinal bars it will be seen thatthe base of the hollow square resulting as before will have a conicalform. In case the members or bars are secured together the joints bymeans of 2 rivets l6 which are suihciently longer than the depth of theslots I so that when they are driven home their lower ends truncatedconical space resulting from-the slot ends of the rivets forms. Thisarrangement, it will be seen, forms a very strong rigid joint. Theexpansion of the IS tends to place the members under compression asbefore.

It will be apparent that the advantages and details of this inventionmay be accomplished by using recesses at the joints which are other thansquare in cross-section. For example, themembers 2, without being firstslotted, may-be assembled in the members i in the slots as shown andthen bored at the joint to form a recess which is curved on a pair ofopposite sides and flat on the remaining sides. Likewise, the recess maybe formed by any suitable method so as to be circular in cross-sectionwhile obtaining the same advantages, whether the locking means be in theformv of a screw or a rivet. It is, of course, apparent that theinvention; is not limited to use in grills and gratings but may beemployed at any place where it is desired to interlock a pair ofstructural members.

From the above description it will be apparent to thos I skilled in theart that the objects of this invention may be secured in other wayswithout departure from the novel scope thereof.

expand to tightly the .section with the transverse members in slots inthe longitudinal members, all slots being open-at one end in a commonplane I do not, therefore, desire to be strictly limited to thedisclosure as given for purposes of illustration but rather to the scopeof the claims grantedme.

What I claim is:

1. A structure of the type described, comprising a plurality oflongitudinal members and a plurality of transversemembers, saidlongitudinal members having slots at the'points of interto form openended recesses, and preformed locking members lying in said recesses andtightly engaging the walls thereof.

LAURENCE S. LACHMAN.

which

